Printed Nanocomposite Energy Harvesters with Controlled Alignment of Barium Titanate Nanowires

Piezoelectric nanocomposites are commonly used in the development of self-powered miniaturized electronic devices and sensors. Although the incorporation of one-dimensional (1D) piezoelectric nanomaterials (i.e., nanowires, nanorods, and nanofibers) in a polymer matrix has led to the development of devices with promising energy harvesting and sensing performance, they have not yet reached their ultimate performance due to the challenges in fabrication. Here, a direct-write additive manufacturing technique is utilized to facilitate the fabrication of spatially tailored piezoelectric nanocomposites. High aspect ratio barium titanate (BaTiO₃) nanowires (NWs) are dispersed in a polylactic acid (PLA) solution to produce a printable piezoelectric solution. The BaTiO₃ NWs are arranged in PLA along three different axes of alignment via shear-induced alignment during a controlled printing process. The result of electromechanical characterizations shows that the nanowire alignment significantly affects the energy harvesting performance of the nanocomposites. The optimal power output can be enhanced by as much as eight times for printed nanocomposites with a tailored architecture of the embedded nanostructures. This power generation capacity is 273% higher compared to conventional cast nanocomposites with randomly oriented NWs. The findings of this study suggest that 3D printing of nanowire-based nanocomposites is a feasible, scalable, and rapid methodology to produce high-performance piezoelectric transducers with tailored micro- and nanostructures. This study offers the first demonstration of nanocomposite energy harvesters with spatially controlled filler orientation realized directly from a digital design.